Photographic product and process of using same



Oct. 3, 1967 E. H. LAND 3,345,165

PHOTOGRAPHIC PRODUCT AND PROCESS OF USING SAME Filed July 31, 1965 2 Sheets-Sheet 1 INTERMEDIATE LAYERS HAVING INCREASED OR GRADED' HYDROPHILLIC CHARACTER OUTWARD FROM THE BASE LAYER ALKALI-IMPERMEABLE BASE LAYER INVENTOR. 5M fi a E. H. LAND 2 g R m MM 2. N m m E 8 3 m w NM lr NQ m t on a 5 0n mm 2 7} Oct. 3, 1967 PHOTOGRAPHIC PRODUCT AND PROCESS OF USING SAME Filed July 31, .1963

United States Patent 3,345,165 PHOTOGRAPHIC PRODUCT AND PROCESS OF USING SAME Edwin H. Land, Cambridge, Mass., assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Filed July 31, 1963, Ser. No. 298,967 13 Claims. (Cl. 96-29) This invention is concerned with photography and, more particularly, with novel image-receiving elements and diffusion transfer processes employing said novel imagereceiving elements.

Diffusion transfer processes for forming transfer images in a camera are now well known. In general, these processes have involved exposing a succession of areas of a photosensitive image-recording sheet, superposing each exposed area with an area of a second sheet and distributing a processing liquid between the superposed sheets in order to produce a positive transfer print in an imagereceiving layer on the second sheet by a diffusion-transfer process. The materials employed comprise an imagerecording sheet including an image-forming material such as a heavy metal salt .(e.g., silver halide), a second or image-receiving sheet for supporting an image-receiving layer containing a diffusion-transfer image, and a processing liquid providing a developing agent for the photosensitive material and including an alkali for rendering the developing agent reactive. It has been proposed to incorporate all of the materials for producing a transfer print including the photosensitive image-recording material, image-receiving material, developing agent, alkali, transferable image-forming substances, and/ or agents capable of forming transferable image-forming substances and even water, in layers or strata comprising the image-recording and second sheets. However, when water or more particularly, an aqueous alkaline liquid, has been included in a stratum or component of one of the two sheets, it has been necessary to provide a barrier for isolating the liquid from other strata and agents incorporated therein, together with means for removing the barrier and bringing all of the reagents into association when processing is to be effected. Heretofore, film assemblages of this general type have had a mechanically complex and expensive construction and have required correspondingly complex and expensive apparatus to achieve their exposure and processing.

A principal object of this invention is to provide novel photographic elements which include an image-receiving layer and which are impregnated with an aqueous alkaline liquid.

Another object .of the invention is to provide novel and improved diffusion transfer processes wherein successive areas of an image-recording sheet including a photosensitive image-forming material, are exposed, said image-recording sheet preferably also including a developing agent therefor, and processing each exposed area by pressing the image-recording sheet into contact with an area of a second sheet impregnated with an aqueous alkaline liquid.

A further object of the invention is to provide a novel and improved photographic product in the form of a film assemblage comprising an image-recording sheet including an image-forming material and a developing agent therefor, and a second sheet including an image-receptive stratum carrying an aqueous alkaline liquid, said second sheet being impregnated with a liquid having a very high pH, i.e., at least 12.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process comprising the several steps and the relation and order of one 3,345,165 Patented Oct. 3, 1967 or more of said steps with respect to each of the others, and the product possessing the features, properties and the relation of components whiich are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a sectional view of one embodiment of an image-receiving element embodying the invention; and

FIG. 2 is a sectional view of the camera taken substantially midway between the upper and lower sides thereof and showing a film assemblage within the camera.

This invention is particularly concerned with producing multicolor photographic transfer prints according to the process disclosed in US. Patent No. 2,983,606 issued May 9, 1961, to Howard G. Rogers; and utilizing integral multilayer negatives incorporating dye developers such as are disclosed therein and in the copending US. application of Edwin H. Land and Howard G. Rogers, Ser. No. 565,135, filed Feb. 13, 1956.

In the process the multilayer negative (sheet) is exposed and superposed with a second sheet including a receiving layer for image-forming dyes transferred by diffusion from the negative sheet; and a liquid reagent is distributed between the two sheets for permeation into the layers of the negative containing the photosensitive materials and dye developers and the image-receiving layer. The liquid reagent is alkaline in nature and serves to render the other reagents, particularly the developers, reactive to develop the exposed silver halide, thereby immobilizing image-forming dyes in areas where image development occurs and causing image-forming dyes in unexposed areas to transfer by diffusion to the image (dye)-receiving layer. The process performed in this invention and the novel products useful therein differ from known processes and products basically in the manner in which the liquid is supplied for permeation into the negative layers. Heretofore, this has been accomplished by providing a quantity of the liquid including a thickening agent in a layer between the two sheets and spreading the thickened (viscous) liquid in a thin layer over each exposed area by moving the sheets in superposition relative to and between a pair of pressure-applying members. It has been the practice to provide the liquid for processing successive areas in either of two ways, these being in a succession of rupturable containers mounted on one of the sheets for movement together with the sheets between the pressure- .applying members, or in separate containers which are moved with respect to the sheets for dispensing their liquid contents between the sheets for subsequent distribution.

According to the present invention, the aqueous alkaline liquid required for processing is carried by the imagereceiving layer itself. This makes possible a very simple film assemblage essentially comprising two sheets and a container for the image-receiving sheet and liquid; as compared with existing film assemblages including such components as masks, containers, liquid-trapping devices, indexing members and the like, requiring careful and precise fabrication and assembly to insure proper operation, registration and location of the various components during processing. The processing components of the camera for use in practicing this invention are correspondingly simple The copending applications of Edwin H. Land, Ser. No. 298,968, now Patent No. 3,254,583, and of Vaito K. Eloranta, Ser. No. 298,969, now Patent No. 3,227,605, both filed concurrently herewith, disclose and claim apparatus useful in conjunction with the novel image-receiving elements of this invention and for performing diffusion transfer processes employing said novel image-receiving elements.

The liquid, examples of which are given hereinafter, carried by the image-receiving layer is highly alkaline, this alkalinity being achieved by the inclusion in the liquid of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, preferably in sufficient quantity to achieve a pH of at least 12. In order to maintain the liquid in this highly alkaline condition for appreciable periods prior to use, suitable precautions must be taken to prevent pH reduction resulting from absorption of carbon dioxide in the processing liquid. One technique for excluding carbon dioxide, such as is found in the atmosphere, from the liquid is to include within the camera a container and/ or a container closure for protecting the liquid-carrying, image-receiving sheet from the atmosphere while allowing successive areas of the image-receiving sheet to be withdrawn from a container (gas impermeable) in the camera and pressed into superposition with successive exposed areas of the image-recording sheet, as disclosed in the aforementioned copending applications. The container and container closure may comprise components of the camera or cooperating components of both the camera and film assemblage employed therein, while achieving a primary object in providing the simplest and least expensive (expendable) film assemblage capable of being processed in the least complicated and expensive camera.

A typical multilayer negative for producing multicolor transfer prints includes blue-sensitive, green-sensitive and red-sensitive silver iodobromide emulsion layers having positioned behind them, respectively, a yellow dye developer, a magenta dye developer and a cyan dye developer; gelatin interlayers positioned between the yellow dye developer layer and the green-sensitive emulsion and between the magenta dye developer layer and the red-sensitive emulsion; and a support for the emulsion layers, dye developer layers, and gelatin inner layers. Multilayer negatives of this type are disclosed, for example, in FIG. 9 of the aforementioned US. Patent No. 2,983,606. Multicolor negatives of the type used in Type 48 Polaroid Polacolor film are particularly useful.

The image-receiving element or sheet comprises a support, preferably of a material which is chemically inert to, is insoluble in and impermeable to aqueous alkaline liquids, and an image-receiving layer of a material receptive to the aforementioned dye developers, securely adhered to the support and s constituted, by virtue of its composition and thickness, as to retain an amount of liquid sufiicient to process the negative. It has been found that where the image-receiving layer is water-permeable and alkali-permeable, unexpectedly good shelf life with an adequate amount of high pH processing composition present may be obtained by positioning intermediate said support and image-receiving layer at least one layer which is partially permeable to water and alkali. In the preferred embodiments, a plurality of such intermediate layers are provided, the permeability (to said processing liquid) and degree of swelling increasing progressively outward from the support. Such image-receiving elements have been found to exhibit good wet adhesion in the presence of high pH alkali metal hydroxide solutions. In a preferred embodiment of the image-receiving sheet, the aqueous alkaline liquid-permeable layer thus has a graded permeability ranging from an impermeable material on a support such as paper, to a highly permeable material swollen by the aqueous alkaline liquid, and comprises a combination of strata of different composition and permeability bonded to one another and the support with the degree of swelling increasing progressively outward from the support. The image-receiving elements of this inven-. tion thus may be described as comprising a hydrophilic outer or image-receiving layer, intermediate layers of graded progressively decreasing hydrophilic character, and a hydrophobic base layer.

The water-impermeable and alkali-impermeable base layer may be coated on a support, such as paper or a plastic, or it may constitute the support. In either instance, the surface or a thin surface portion of the base layer may be chemically converted to a form providing desired physical properties, e.g., good wet adhesion to the layers subsequently coated thereon. Thus, where the base layer is cellulose acetate, the surface thereof may be hydrolyzed or regenerated to cellulose. Techniques and procedures for effecting such surface conversions, e.g., alkaline hydrolysis, are well known and therefore they need not be described here.

The various layers of the image-receiving element are composed of materials, preferably polymeric, which are chemically stable to the aqueous alkaline processing solutions. Thus, the use of gelatin is not contemplated since gelatin will hydroyze in alkali over a period of time, giving products unsuitable for use in this invention. On the other hand, partially hydrolyzed polyvinyl acetate may be employed in certain locations since the fully hydrolyzed product, i.e., polyvinyl alcohol, has the requisite alkali stability.

The graded permeability of hydrophilic character may be obtained by using a hydrophobic polyvinyl butyral base, i.e., it has sufiicient butyral content to be non-swellable, and intermediate layers of partial polyvinyl butyrals in which the proportion of butyral to hydroxyl groups increases outward from the hydrophobic base layer.

As example of materials suitable for use as the waterimpermeable and alkali-impermeable base layer, mention may be made of polyvinyl butyral, polyethylene, ethyl cellulose, papers formed of polyethylene fibers, and paper-like sheets composed of polyethylene encapsulated cellulose or other fiber. Other useful materials will readily suggest themselves to one skilled in the art.

A particularly useful image-receiving layer comprises a mixture of polyvinyl alcohol and poly-4-vinylpyridine. With such an image-receiving layer, particular useful in- 0 termediate layers comprise mixtures of poly-4-vinylpyridine and polyvinyl alcohol, the proportion of polyvinyl alcohol increasing progressively outward from the support, as will be indicated in more detail in the examples below.

A cross-sectional view of one embodiment of the novel image-receiving element is shown in FIG. 1, wherein an alkali-impermeable and water-impermeable base 1 carries a plurality of intermediate layers 3a, 3b, 3c and 3d which exhibit progressively increased alkali-permeable outward from said base 1, over which is coated a water-permeable and alkali-permeable image-receiving layer 5. The aqueous alkaline processing solution is impregnated into all of the alkali-permeable layers. The distribution of the processing composition in these layers follows the alkali-permeability, with the maximum amount of solution per unit area being present in the image-receiving layer 5. This method of distributing the processing composition also helps to insure a supply of processing solution adequate to process the exposed negative without having excess solution collect on the surface of the image-receiving layer.

It is a characteristic of the liquid-impregnated imagereceiving elements of this invention that the surface of the image-receiving layer is substantially dry, i.e., there is not moisture or free liquid visible on the surface and the surface is substantially dry to the touch.

A camera suitable for use with the novel image-receiving elements of this invention (and disclosed and claimed in the aforementioned application of Edwin H. Land, Ser. No. 298,968, filed concurrently herewith) is shown in FIG. 2. Such a camera, designated 10, comprises a housing including three relatively movable sections designated a forward section 12, a rear section 14 and an end section 16. The forward section of the camera housing comprises a forward wall 18 having a generally rectangular opening therein including a recessed section defined by an upper side wall (not shown), a lower side wall 22, end walls 24 and 26 and a rear wall 28 provided with a rectangular exposure aperture 30. The camera is of the folding type and includes a conventional lens and shutter assembly 32 coupled with rear wall 28 by a bellows 34 which is collapsible (the usual erecting mechanism is not shown) to permit the bellows and the lens and shutter assembly to be contained within the recess in the forward housing section.

The rear housing section includes a rear wall 36 having a curved end section 3-8 (at the left in the drawings) at which the rear housing section is pivotally secured to the forward housing section by a hinge 40. The forward and rear housing sections, specifically forward wall 18, upper side wall, lower side wall 22, wall 24 and end section 38 of rear wall 36 cooperate to provide a storage chamber 42 for mounting and enclosing a roll of a photosensitive image-recording sheet 44 of the type described. The rear housing section also includes a portion designated 46 located at the end of rear wall 36 opposite end section 38 which projects rearwardly from rear wall 36 and includes a wall 48 having an L-shaped cross section and upper and lower side walls 50 which are disposed above and below the upper and lower side walls. The rear housing section is pivotable between the closed or operative position in which the forward and rear housing section cooperate to provide closed storage chamber 42; and an open position at which access is provided to chamber 42 for loading a roll of image-recording sheet 44 into the storage chamber and threading the sheet or a leader attached thereto through the camera between rear walls 28 and 36 across exposure aperture 30'. The rear surface of rear wall 28 and the forward surface of rear wall 36 are located generally at the focal surface of the lens of assembly 32 and cooperate to locate successive areas of the image-recording sheet in position for exposure to light transmitted by the lens through aperture 30.

The forward housing section 12 includes an end wall designated 60 spaced from end wall 26 and cooperating with the latter, forward wall 18 and upper wall (not shown) and lower wall 22 to provide another chamber 62 for enclosing components of the apparatus. End wall 60 also functions to provide a wall for a sealed container (to be described hereinafter). End walls 26 and 60 extend rearwardly to join rear wall 36 at the end of the forward housing section 12 furthest from chamber 42. The inner, upper and lower walls (not shown) of end section 16, forward wall 64, end wall 66, and rear wall 68 cooperate to provide an open storage chamber 82 for a supply of the image-recording sheet designated 84. End section 16 is coupled with forward housing section 12 by a hinge 86 constructed to provide for limited linear movement of the end section relative to the forward section as well as pivotal movement of the two sections with respect to one another. Hinge 86 is secured to forward walls 18 and 64 of, respectively, the forward and end housing sections and permits the end section to be pivoted with respect to the forward section between the operative or closed position and the open or inoperative position. In the closed position of the end section of the housing, end wall 60 of the forward section cooperates with the end section to provide a closure for storage chamber 82, whereas in the open position of the end section, chamber 82 is open to permit loading of a supply of an imagereceiving sheet 84 into chamber 82.

End section 16 of the housing includes a rearwardly projecting portion 88 comprising upper and lower walls joined by an L-shaped wall 92 extending rearwardly from rear wall 68 and then parallel with the rear wall and co- 6 operating with said upper and lower walls to provide a chamber 94 for enclosing components of the apparatus.

The camera includes means for retaining the housing sections in the closed or operative position shown in FIG. 2. These means comprise extensions 96 on the upper and lower portions of L-shaped wall 92 which extend, in the closed position of the housing, outside of wall 48 of portion 46 of rear housing section 14. In order to close the housing, the rear housing section 14 is pivoted from the open position to a closed position whereupon end section 16 is pivoted from an open position to a closed position so that extensions 96 extend outside of wall 48 preventing pivotal movement of rear housing section from its closed position. Latch means are provided for retaining end housing section 16 in its closed position and may comprise a pair of generally L-shaped latching arms each having a hook on its inner end.

In the operative position of the housing sections, walls 48, 92 and extensions 96 of wall 92 cooperate to define a slot 114 connecting with chamber 94 defined by portions 46 and 88 of the rear and end housing sections. Slot 114 is dimensioned to permit withdrawal of the image-recording and image-receiving sheets in superposition from the camera housing and a cutting bar having a sharpened, serrated edge is provided within slot 114 on wall 48 for facilitating the severance of sheet materials extending from the camera housing through the slot.

Photosensitive image-recording sheet 44 is supplied in a coiled condition in the usual manner, e.g., on a spool, is housed in chamber 42 and is threaded from the chamber across opening 30 between rear walls 28 and 36 into chamber 94. The liquid impregnated image-receiving sheet 84 is supplied in a coiled condition in a container which is substantially impermeable to the processing liquid, water vapor and gases, particularly carbon dioxide (and oxygen where a silver halide developing agent is present in the processing liquid). A typical container for the liq uid impregnated image-receiving sheet is illustrated in FIG. 2. This container, designated 118, includes a generally cylindrical peripheral wall and two circular end walls. Wall 120 is provided with an axial slot defined by a pair of overlapping outer and inner lips designated, respectively, 124 and 126. The edge portion of the outer lip is thickened and the inner lip is provided with a rib to stifien the two lips and retain them in a closed position in engagement with a portion of image-receiving sheet 84 extending from the container through the passage between the lips. The edge of inner lip 126 closest the outer lip is provided with a sharpened corner designed to function as a squeegee for removing any liquid from a surface of image-receiving sheet 84. Container 118 may be formed of any suitable material particularly organic plastics, such as polyethylene, which are air and water vapor impervious and are compatible with aqueous alkaline liquids. The image-receiving sheet is supplied in a coiled condition in container 118 with a leading end portion of the sheet extending from the container through the passage between lips 124 and 126. Additional means may be provided for sealing the passage against the admission of air and the leakage of water or water vapor and in the form shown these sealing means may comprise a seal of some material, such as wax, which may be introduced in a softened or molten condition into the passage between the lips 124 and 126 in surrounding relation to the sheet to fill the passage and form a rupturable bond between the sheet and container to prevent the passage of air and water between the lips.

Receiving sheet 84 may be coiled with the liquid impregnated image-receiving layer facing inwardly or outwardly and is shown in FIG. 2 with the liquid impregnated layer facing outwardly. Since the container must be opened to permit the withdrawal of the image-receiving sheet and thus possibly permit escape of water vapor and/ or admission of air, it may be desirable to provide a reservoir of excess processing liquid within the container together with means for gettering carbon dioxide so that any carbon dioxide gaining admission to the container does not react with the hydroxide in the processing liquid to reduce the pH thereof. The image-receiving sheet is preferably coiled tightly upon itself to help prevent contact between the liquid impregnated image-receiving layer and the atmosphere of the container. In order to prevent loss (by evaporation) of processing liquid from the image-receiving layer, the atmosphere of the container is preferably maintained saturated with water vapor by the provision of a reservoir of water or processing liquid. This reservoir of excess processing liquid or water may comprise the image-receiving layer itself which may be impregnated with excess liquid which could be removed by squeegeeing during withdrawal of the receiving sheet from the container. In this embodiment, squeegees would be provided on both lips 124 and 126 for removing liquid from both surfaces of the image-receiving sheet so that the sheet, upon withdrawal from the container, is substantially dry to the touch with all the liquid required for processing being retained within the image-receiving layer. In an alternative embodiment, water or processing liquid may be provided in a reservoir apart from the image-receiving sheet. Such a reservoir may comprise, for example, a liquid impregnated absorbent material shown wrapped around the outside of the coiled image-receiving sheet, but in an alternative embodiment could be disposed within the coiled receiving sheet.

In order to maintain the high pH level of the liquid carried by the image-receiving layer, it may be necessary to provide a getter for any carbon dioxide which enters the container. Since hydroxides, particularly the hydroxides comprising the processing liquid are highly reactive with carbon dioxide, such a getter may also comprise a hydroxide contained, for example, within the reservoir of liquid which provides for the water vapor saturated atmosphere within the container. Alkaline earth metal hydroxides particularly are suggested for use as getters and include hydroxides which combine with carbon dioxide to form carbonates which are less soluble than the carbonates formed by the alkali metal hydroxide in the processing liquid. For example, when potassium hydroxide is used in the processing liquid, calcium hydroxide may be provided for reacting with carbon dioxide in order to prevent reaction of the potassium hydroxide with carbon dioxide within the container. Barium hydroxide is also suggested as a getter when potassium hydroxide is employed in the processing liquid. Sodium hydroxide may be incorporated in the processing liquid instead of potassium hydroxide to provide for the high pH thereof, in which case any of potassium hydroxide, barium hydroxide and calcium hydroxide may be incorporated in the container as a getter for carbon dioxide.

Container 118 in which liquid impregnated sheet 84 is supplied is unsealed at the commencement of withdrawal of the image-receiving sheet therefrom and in the form shown remains unsealed thereafter. Accordingly, the camera in which the container is employed includes either: means for sealing the container against the escape of water vapor and the admission of carbon dioxide, or a container for holding container 118 and which may be sealed against the escape of water vapor and the admission of carbon dioxide, between times when the image-receiving sheet is being withdrawn from container 118 and/or the container within the camera. The camera shown in FIG. 2 includes a container which is substantially impervious to water vapor and carbon dioxide and which may be sealed against the admission or escape of water vapor and carbon dioxide and may be opened to permit the withdrawal movement of the imagereceiving sheet therefrom. This container comprises storage chamber 32 and is defined by end wall 60, inner upper wall (not shown), inner lower wall (not shown) and end wall 66. Means are provided for sealing stor- 8 age chamber 82 and preferably comprise in the form shown a pair of seals formed of an elastomeric material which is compatible with or unaffected by hydroxide, is substantially impervious to water vapor and carbon dioxide, and is highly resistant to assuming a permanent set.

To process an exposed area of image-recording sheet 44 to produce a transfer image in a corresponding area of the image-receiving sheet, the two sheets are pressed into superposition with one another. This processing is accomplished by a pair of pressure rolls 164 and 166. Each of rolls 164 and 166 is shown as comprising a metal shaft covered by an elastomeric material such that the rolls are slightly compressible and, in fact, the resiliency of the elastomeric material may be employed to apply the necessary pressure to the two sheets. Roll 164 is pivotally mounted on rear housing section 14 between upper and lower side walls 50 for movement into juxtaposition with roll 166 which is also mounted within chamber 94 of the inner upper and inner lower walls.

In the operation of the camera, image-receiving sheet 84 extends from chamber 82 into superposition with image-recording sheet 44 between rolls 164 and 166. The rolls are rotated in engagement with the superposed sheets in order to superpose an exposed area of the photosensitive sheet with an area of receiving sheet and simultaneously advance the sandwich thus formed from the camera through slot 114 and advance the next succeeding area of the image-recording sheet into position for exposure in alignment with aperture 30. Suitable gear means (not shown) may be provided rolls, preferably with a gear ratio such that one complete revolution of a crank rotates roll 164 sufliciently to advance an exposed area of the image-recording sheet into superposition with the image-receiving sheet and from the camera. It should be noted that roll 164 is located as close as possible to the end edge of exposure aperture 30 and the opening into chamber 82 so as to minimize the length of sheet materials constituting waste between successive exposed areas of the photosensitive sheet and the length of the image-recording sheet superposed therewith.

The camera shown in FIG. 2 is described in more detail in the aforementioned copending applications filed herewith.

The film assemblage, including the sheet materials employed in the camera shown and described, is supplied with a leading end portion thereof, or leader attached thereto, extending from container 118 and coupled with a leader or the leading end of the image-recording sheet. To load the camera, the coil of image-recording sheet is introduced into chamber 42; the rear housing section is pivoted into closed position; the container of imagereceiving sheet is loaded into chamber 82; end housing section 16 is then pivoted into closed position, and latching arms are pivoted in a counterclockwise direction to retain the camera in closed position. The camera housing sections are thus closed with the coupled leaders extending between rolls 164 and 166 through slot 114. An area of the image-recording sheet is then advanced into position for exposure, e.g., by pulling on the coupled leaders or by rotating suitable gear means. Following exposure of this and each succeeding area of the image-recording sheet, the coupled leaders are again advanced, thereby processing each exposed area of the image-recording sheet by pressing it into superposition with an area of the image-receiving sheet to form a sandwich and advancing the sandwich from the camera through slot 114. The superposed areas of the two sheets comprising the sandwich may be severed from portions of the sheets remaining within the camera housing by drawing the sandwich against a cutting bar (not shown).

The sheets are retained in superposition during a processing period of predetermined duration at the end of which the sheets are separated to reveal a transfer print on the image-receiving sheet.

the supports of both The image-receiving sheet 84 may also be supplied in a coiled condition in a container in the form of a bag. The sheet material comprising the bag may be a multiply material formed, for example, of paper and/ or metal foil with an inner ply of a polymeric material, preferably one which is thermoplastic and can be bonded to itself and other materials by application of heat and pressure. The completed container is formed with a pair of lips releasably secured to the image-receiving sheet and defining a mouth through which the image-receiving sheet may be withdrawn. Alternatively, a clip or other means may be provided for holding the lips in a closed position prior to loading of the container into a camera. A reservoir for excess water or processing liquid and a getter for carbon dioxide may take the'form of a sheet of an absorbent material impregnated with the desired liquid disposed in surrounding relation to the coiled image-receiving sheet.

The film assemblage described herein together with the camera are intended for intermittent frame by frame exposure and processing, with the film assemblage itself being substantially simplified, as compared to existing self-developing roll film assemblages, in that its essential elements are limited to an image-recording sheet, a liquid impregnated image-receiving sheet and a container for the latter. Masks, fluid collecting and retaining devices, indexing references and the like, heretofore associated with this type of roll film assemblage, have been made unnecessary and the camera itself is simplified particularly with regard to the mechanism for pressing the two sheets together and distributing the processing liquid between the sheets.

The camera may be modified to provide for withdrawal of the sheets by manually engaging and pulling on the sheets. In this form of camera, an indexing system may be provided in association with the rolls, and manual-1y operable means would be provided for at least opening the container to permit withdrawal of the image-receiving sheet.

The sandwich comprising the two superposed sheets may be advanced directly from the camera in which exposure and processing is accomplished and accordingly,

the photosensitive and image-receiving sheets are each formed of a material or provided with a layer which is opaque to actinic light.

The following examples of the preparation of imagereceiving elements in accordance with this invention are given for purposes of illustration only.

EXAMPLE 1 A liquid-impregnated image-receiving sheet was prepared as follows: a sheet of =baryta paper was coated on both sides with a solution comprising 5 g. of polyvinyl butyral in 100 cc. of ethanol, to render the support impermeable to the aqueous alkaline liquid. To the thuscoated base was applied a coating of a solution comprising:

Polyvinyl Butyral z g 5 Poly-4-vinylpyridine g 5 Ethanol cc 200 To the foregoing coating was applied a coating of a solution comprising 10 g. of poly-4-vinylpyridine in 200 cc. of ethanol. Three additional coatings were then applied comprising in order 3:1, 2:1 and 1:1 mixtures of, respectively, solutions A and B comprising:

'be substantially dry to the touch;

Each of the aforesaid 3:1, 2:1 and 1:1 mixtures was diluted by an equal quantity of water before application. All of the layers were applied by a conventional reverse roll coating technique in which a doctor was employed spaced from the coating roll by a .003 inch gap; and the six layers comprising the image-receiving layer were found after drying to have an aggregate thickness of about .0007 inch.

The image-receiving sheet thus prepared was immersed for 5 minutes in an aqueous alkaline processing composition comprising:

KOH g 7.26 Sodium tetraborate g 2.0 Benzotriazole g 2.3 N-benzyl-u-picolinium bromide g 2.3 Water cc Before pressing the liquid-containing, image-receiving sheet into contact with an exposed photosensitive sheet of the type used in Type 48 Polaroid Polacolor film to effect the processing of the latter and the formation of a dye transfer image on the image-receiving sheet, both surfaces of the image-receiving sheet were squeegeed to remove excess liquid from the image-receiving layer and render the surface of the support tactually dry. The processing liquid required for treating the photosensitive sheet is contained entirely within the swollen, imagereceiving layer so that this layer too may appear to and, in any event, no free liquid remainedv on the surface of the imagereceiving layer following the squeegeeing operation. The exposed photosensitive sheet and the impregnated imagereceiving element were passed between soft rubber rolls. The tension on the rubber rolls was so set that there was no real squeezing action but a good surface contact was effected. Just enough liquid was squeezed out to insure a good wet contact between the superposed sheets. The pressure was less than would be required to squeeze out a major portion of the liquid. After an imbibition period of approximately one minute, the image-receiving element was separated and contained a positive multicolor transfer image. The surface of the separated imagereceiving element was very slightly damp (apparently because the photosensitive element did not absorb all of the liquid initially present in the image-receiving element) but dried completely within a minute or two.

EXAMPLE 2 The procedure described in Example 1 was repeated except that the polyvinyl butyral-coated baryt-a paper was replaced by a cast sheet of polyvinyl butyral film.

EXAMPLE 3 The procedure describedin Example 1 was repeated except that the polyvinyl butyral back coat was replaced by ethyl cellulose.

EXAMPLE 4 The procedure described in Example 2 was repeated except that the polyvinyl butyral sheet was pigmented to provide an opaque base.

EXAMPLE 5 The procedure described in Example 1 was repeated except that the polyvinyl butyral-coated baryta paper was replaced'by a paper-like sheet of polyethylene fibers.

EXAMPLE 6 In lieu of the processing composition set forth in Example 1, the following may be used:

1 1 EXAMPLE 7 In lieu of the processing composition set forth in Example 1, the following may be used:

KOH -g 7.26 Sodium tetraborate g 2.0 Benzotriazole g 2.3 N-benzyl-a-picolinium bromide g 2.3 Sodium thiosulfate g 0.5 Water cc 100 EXAMPLE 8 The procedure described in Example 1 was repeated except that the polyvinyl-butyral coated baryta paper was replaced by a Saran-coated Mylar (trade name of E. I. du Pont de Nemours & Co. for a polyethylene terephthalate film support), which was coated (over the saran sub-coat) with a layer of polyvinyl butyral containing dispersed titanium dioxide. Excellent wet adhesion was obtained.

In the above examples, the image-receiving element was immersed in the liquid processing composition for about minutes; it was found that longer soaking times did not result in appreciably more liquid being absorbed. This immersion time may be varied, depending upon the particular composition of the image-receiving element. The minimum time necessary to absorb the desired amount of liquid thus may be readily determined by one skilled in the art.

It has been found that soaking of the image-receiving element in the processing composition for about 2 /2 hours is a good test of determining the adequacy of the wet adhesion of the various layers. Image-receiving elements which show adequate adhesion under these conditions have generally been found to show adequate wet adhesion over longer periods.

Where the base for the image-receiving element contains a stratum or core which is permeable to the processing solution, care should be used to avoid or minimize liquid absorption through the edges of that stratum, as such liquid absorption may eventually be the cause of bubbles or other weakening of adhesion between the various layers. For this reason, it is preferred that paper bases be impregnated with a plastic which minimizes or prevents such edge absorption of liquid.

Care should be exercised in the selection of solvents to minimize undesired solvent retention by the coated image-receiving sheet. Thus, for example, ethanol is retained by polyvinyl butyral and acts as a plasticizer therefor; the ethanol is not readily given up by the polyvinyl butyral, even on baking. Such retention of coating solvent may result in variations in properties of the liquid impregnated image-receiving element over a period of time.

The liquid impregnated image-receiving element preferably is not passed over sharp edges, since this may cause delamination.

It will be recognized that the liquid-impregnated imagereceiving elements of this invention cannot contain a pH control layer of the type disclosed and claimed in the copending application of Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962. These liquid-impregnated image-receiving elements, however, are particularly useful with photosensitive elements containing a polymeric acid layer adjacent the support, such as those disclosed and claimed in the copending application of Edwin H. Land, Ser. No. 277,209, filed May 1, 1963. The following example of the preparation of such a photosensitive element is given for purposes of illustration only.

EXAMPLE 9 300 g. of high viscosity poly-(ethylene/maleic anhydride) [commercially available from Monsanto Chemical Co., St. Louis, Mo., under the trade name DX-840-31 Resin] was dissolved in 1500 cc. of acetone. 150 g. of n- 12 butyl alcohol and 1 cc. of phosphoric acid were added and the mixture was refluxed for 14 hours. The resulting solution of a polymer containing recurring segments of the formula:

was allowed to cool and then coated on a cellulose nitrate subcoated baryta paper to give a polymeric acid layer about 0.8 mil thick. A thin layer of cellulose acetate was then coated using a solution containing 3% cellulose acetate dissolved in a mixture of methanol and ethyl acetate to provide a spacer layer. Cyan, magenta and yellow dye developer layers, gelatin interlayers, and red, green and blue-sensitive silver halide emulsions were then applied to form a photosensitive element of the type employed in the preceding examples.

The use of a photosensitive element of the type described in said Ser. No. 277,209 and in Example 8 results in the pH of the surface of the separated image-receiving element being appreciably lower. Transfer image colors are brighter, and the surface is much drier because of the additional liquid absorbed by such photosensitive elements.

Although this invention has been illustrated in connection with camera applications, it will be understood that the liquid-impregnated image-receiving elements also are very useful in continuous processing applications, such as photofinishing processing of color print copies.

Use of the liquid-impregnated image-receiving elements of this invention provides a number of advantages. One important advantage which may be mentioned is the elimination of excess processing composition; because of the high pH, such compositions are potentially harmful to skin tissues. In addition, the manner of supplying the liquid processing composition and the distribution thereof maybe more uniform than if a conventional rupturable container were used. Examination of the transfer images prepared in the above examples also has given indications of improved color separation. Because of the intimate contact between the two sheets and the absence of a layer of viscous reagent therebetween, lateral diffusion of transferring dyes is minimized.

The use of high pH solutions of alkali metal hyroxides impregnated in the image-receiving element makes possible performance of processes which do not work or do not work well at the lower pH levels provided by use of solutions employing organic amines and impregnated in gelatin layers.

It is a characteristic feature of this invention that the image-receiving layer serves two functions: (1) it releasably retains over a period of time the liquid necessary to process a photosensitive element, and (2) it gives up that liquid in exchange for the image dyes transferred by diffusion to the image-receiving layer through that liquid.

Since certain changes may be made in the above processes and roducts without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. As a new product, a sheet-like element releasa-bly retaining an aqueous alkaline composition and adapted to be used in processing an exposed photosensitive silver halide stratum, said element comprising:

(a) a water-impermeable and alkali-impermeable base layer,

(b) a water-permeable and alkali-permeable outer layer,

(c) a plurality of layers intermediate said base layer and said outer layer, each said intermediate layer being at least partially permeable to water and alkali,

(d) an aqueous alkaline composition contained in said outer and intermediate layers,

(c) said outer and intermediate layers being swollen by said aqueous alkaline composition, said outer layer being appreciably swollen and said intermediate layers inward from said outer layer being progressively less swollen than said outer layer,

(f) said base, outer and intermediate layers being chemically stable to said aqueous alkaline composition,

(g) the surface of said outer layer being substantially dry to the touch.

2. A product as defined in claim 1, wherein said base layer is carried by a paper support.

3. A product as defined in claim 1, wherein said alkali is an alkali metal hydroxide.

4. A product as defined in claim 1, wherein said aqueous alkaline composition has a pH of at least 12.

5. A product as defined in claim 1, wherein said aqueous alkaline composition includes a quaternary ammonium compound.

6. As a new product, an image-receiving element releasably retaining an aqueous alkaline solution and adapted to be used in processing an exposed photosensitive silver halide element containing at least one dye developer, said element comprising:

(a) a water-impermeable and alkali-impermeable base layer,

(b) a water-permeable and alkali-permeable outer layer comprising a mixture of polyvinyl alcohol and poly-4-viny1pyridine.

(c) a plurality of layers intermediate said base layer and said outer layer, each said intermediate layer being at least partially permeable to water and alkali and composed of a mixture of polyvinyl alcohol and poly-4-vinylpyridine, the relative amount of said poly- 4-vinylpyridine progressively increasing in each intermediate layer inwardly from said outer layer,

(d) an aqueous alkaline solution of an alkaline metal hydroxide contained in said outer and intermediate layers, said solution having a pH of at least 12,

(e) said outer and intermediate layers being swollen by said aqueous alkaline solution, said outer layer being appreciably swollen and said intermediate layers inward from said outer layer being progressively less swollen than said outer layer,

(1) the surface of said outer layer being free of visible moisture, and

(g) said aqueous alkaline solution being present in an amount sufiicient to process said exposed photosensitive element.

7. An image-receiving element as defined in claim 6, wherein said solution includes a quaternary ammonium compound.

8. A photographic product comprising a roll of a photosensitive silver halide element, a roll of an image-receiving element as defined in claim 1, a leading portion of said photosensitive element being so attached to a leading por tion of said image-receiving element that the outer layer of said image-receiving element is in contact with the outer photosensitive surface of said photosensitive element.

9. A diffusion transfer process comprising the steps of exposing a photosensitive silver halide element, bringing said exposed photosensitive element into contact with the liquid-impregnated outer layer of the image-receiving element defined in claim 1, said contact being efiected under pressure sufficient to obtain surface-to-surface wet contact but insuflicient to squeeze a major portion of said liquid out of said image-receiving element, whereby said liquid is absorbed by said photosensitive element and develops the exposed areas thereof, and an imagewise distribution of diffusible image-forming components is transferred by diffusion to said image-receiving element to form a postive transfer image.

10. A process as defined in claim 9, wherein said diffusible-forming components are dye developers.

11. A process as defined in claim 9, wherein said photosensitive element includes a layer of a polymeric acid between the support and the photosensitive layer, whereby the pH of the surface of the image-receiving layer is reduced prior to separation of said photosensitive element and said image-receiving element.

12. A photographic product comprising a hydrophobic base layer, a hydrophilic outer layer containing a mordant for a dye developer adapted to receive a dye image during photographic use, at least two layers intermediate said base layer and said outer layer, said intermediate layers being of progressively increasing hydrophilic character outward from said base layer, said hydrophilic layers releasably containing an aqueous alkaline solution in sufficient volume to process a photosensitive element of the same area.

13. An image-receiving element adapted to be used in processing an exposed photosensitive silver halide element containing at least one dye developer, said element comprising:

(a) a water-impermeable and alkali-impermeable base layer,

(b) a water-permeable and alkali-permeable outer layer comprising a mixture of polyvinyl alcohol and poly-4-vinylpyridine,

(c) a plurality of layers intermediate said base layer and said outer layer, each said intermediate layer being at least partially permeable to water and alkali and composed of a mixture of polyvinyl alcohol and poly-4-vinylpyridine, the relative amount of said poly-4-vinylpyridine progressively increasing in each intermediate layer inwardly from said outer layer, and

(d) said outer and intermediate layers being swellable by an aqueous alkaline solution, said outer layer being appreciably swellable and said intermediate layers inward from said outer layer being progressively less swellable than said outer layer.

References Cited UNITED STATES PATENTS 2,543,181 2/1951 Land 9629 3,003,872 10/1961 Blout et al 9629 3,148,061 9/1964 Haas 96-3 3,179,517 5/1965 Tregillus et al. 96-29 FOREIGN PATENTS 576,537 5/1950 Canada. 623,390 7/ 1961 Canada.

I. TRAVIS BROWN, Primary Examiner. 

1. AS A NEW PRODUCT, A SHEET-LIKE ELEMENT RELEASABLY RETAINING AN AQUEOUS ALKALINE COMPOSITION AND ADAPTED TO BE USED IN PROCESSING AN EXPOSED PHOTOSENSITIVE SILVER HALIDE STRATUM, SAID ELEMENT COMPRISING: (A) A WATER-IMPERMEABLE AND ALKALI-IMPERMEABLE BASE LAYER, (B) A WATER-PERMEABLE AND ALKALI-PERMEABLE OUTER LAYER, (C) A PLURALITY OF LAYERS INTERMEDIATE SAID BASE LAYER AND SAID OUTER LAYER, EACH SAID INTERMEDIATE LAYER BEING AT LEAST PARTIALLY PERMEABLE TO WATER AND ALKALI, (D) AN AQUEOUS ALKALINE COMPOSITIN CONTAINED IN SAID OUTER AND INTERMEDIATE LAYERS, (E) SAID OUTER AND INTERMEDIATE LAYERS BEING SWOLLEN BY SAID AQUEOUS ALKALINE COMPOSITION, SAID OUTER LAYER BEING APPRECIABLY SWOLLEN AND SAID INTERMEDIATE LAYERS INWARD FROM SAID OUTER LAYER BEING PROGRESSIVELY LESS SWOLLEN THAN SAID OUTER LAYER, (F) SAID BASE, OUTER AND INTERMEDIATE LAYERS BEING CHEMICALLY SABLE TO SAID AQUEOUS ALKALINE COMPOSITION, (G) THE SURFACE OF SAID OUTER LAYER BING SUBSANTIALLY DRY TO THE TOUCH.
 9. A DIFFUSION RANSFER PROCESS COMPRISING THE STEPS OF EXPOSING A PHOTOSENSITIVE SILVER HALIDE ELEMENT, BRINGING SAID EXPOSED PHOTOSENSITIVE ELEMENT INTO CONTACT WITH THE LIQUD-IMPREGNATED OUTER LAYER OF THE IMAGE-RECEIVING ELEMENT DEFINED IN CLAIM 1, SAID CONTACT BEING EFECTED UNDER PRESSURE SUFFICIENT TO OBTAIN SURFACE-TO-SURFACE WET CONTACT BUT INSUFFICIENT TO SQUEEZE A MAJOR PORTION OF SAID LIQUID OUT OF SAID IMAGE-RECEIVING ELEMENT, WHEREBY SAID LIQUID IS ABSORBED BY SAID PHOTOSENSITIVE ELEMENT AND DEVELOPS THE EXPOSED AREAS THEREOF, AND AN IMAGEWISE DISTRIBUTION OF DIFFUSIBLE IMAGE-FORMING COMPONENTS IS TANSFERRED BY DIFFUSION TO SAID IMAGE-RECEIVING ELEMENT TO FORM A POSITIVE TRANSFER IMAGE. 